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To evaluate molecular signatures of an individual cell type in comparison to the associated region relevant towards understanding the pathogenesis of Alzheimer's disease (AD), CA1 pyramidal neurons and the surrounding hippocampal formation were microaspirated via laser capture microdissection (LCM) from neuropathologically confirmed AD and age-matched control (CTR) subjects as well as from wild type mouse brain using single population RNA amplification methodology coupled with custom-designed microarray analysis with real-time quantitative polymerase-chain reaction (qPCR) validation. CA1 pyramidal neurons predominantly displayed downregulation of classes of transcripts related to synaptic transmission in AD versus CTR. Regional hippocampal dissections displayed downregulation of several overlapping genes found in the CA1 neuronal population related to neuronal expression, as well as upregulation of select transcripts indicative of admixed cell types including glial-associated markers and immediate-early and cell death genes. Gene level distributions observed in CA1 neurons and regional hippocampal dissections in wild type mice paralleled expression mosaics seen in postmortem human tissue. Microarray analysis was validated in qPCR studies using human postmortem brain tissue and CA1 sector and regional hippocampal dissections obtained from a mouse model of AD/Down syndrome (Ts65Dn mice) and normal disomic (2N) littermates. Classes of transcripts that have a greater percentage of the overall hybridization signal intensity within single neurons tended to be genes related to neuronal communication. The converse was also found, as classes of transcripts such as glial-associated markers were under represented in CA1 pyramidal neuron expression profiles relative to regional hippocampal dissections. These observations highlight a dilution effect that is likely to occur in conventional regional microarray and qPCR studies. Thus, single population studies of specific neurons and intrinsic circuits will likely yield informative gene expression profile data that may be subthreshold and/or underrepresented in regional studies with an admixture of cell types.
Pubmed ID: 21821124
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THIS RESOURCE IS NO LONGER IN SERVICE. Documented on January 4, 2023.Consortium that developed brief, standardized and reliable procedures for the evaluation and diagnosis of patients with Alzheimer's disease (AD) and other dementias of the elderly. These procedures included data forms, flipbooks, guidebooks, brochures, instruction manuals and demonstration tapes, which are now available for purchase. The CERAD assessment material can be used for research purposes as well as for patient care. CERAD has developed several basic standardized instruments, each consisting of brief forms designed to gather data on normal persons as well as on cognitively impaired or behaviorally disturbed individuals. Such data permit the identification of dementia based on clinical, neuropsychological, behavioral or neuropathological criteria. Staff at participating CERAD sites were trained and certified to administer the assessment instruments and to evaluate the subjects enrolled in the study. Cases and controls were evaluated at entry and annually thereafter including (when possible) autopsy examination of the brain to track the natural progression of AD and to obtain neuropathological confirmation of the clinical diagnosis. The CERAD database has become a major resource for research in Alzheimer's disease. It contains longitudinal data for periods as long as seven years on the natural progression of the disorder as well as information on clinical and neuropsychological changes and neuropathological manifestations.
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